Spontaneous depolarization waves of multiple origins in the embryonic rat CNS : Optical imaging with voltage-sensitive dyes.

在发育过程中，相关的神经元活动在中枢神经系统（CNS）的建立中起着重要作用。我们最近报道，在胚胎大鼠中枢神经系统，广泛传播的相关神经元活动，称为去极化波，是由各种感觉神经输入诱发的。去极化波的一个显著特征是它如何广泛地传播到大脑和脊髓。在本研究中，我们研究是否去极化波自发发生在胚胎大鼠中枢神经系统，如果是这样，它的起源。在E15-E16胎鼠中，自发性光信号与颅运动神经元的节律性放电有关，并以类似于诱发去极化波的特征在脑和脊髓中传播。自发波起源于多个部位，包括位于脑桥背内侧和延髓头端腹外侧以及延髓中/尾侧和脊髓的两个限制区域。当脊髓完整时，E16时的波主要起源于腰骶区，尽管与振荡事件相关的波也在颈髓/尾髓中产生。在脊髓横断的标本中，脑桥和延髓的贡献更为显著。这些结果表明，从脑桥到腰骶髓广泛分布的多个神经元群的自发活动触发了去极化波。该网络可能表现为一个自我分配系统，在发育中的CNS中维持相关活动的发生率和复杂模式。

During development, correlated neuronal activity plays an important role in the establishment of the central nervous system (CNS). We recently reported that in the embryonic rat CNS, a widely-propagating correlated neuronal activity, termed the depolarization wave, is evoked by various sensory nerve inputs. A remarkable feature of the depolarization wave is how it spread broadly through the brain and spinal cord. In the present study, we examined whether the depolarization wave occurs spontaneously in the embryonic rat CNS, and if so, where it originates. In E15-E16 rat embryos, spontaneous optical signals appeared in association with the rhythmic discharges of cranial motoneurons, and propagated through the brain and spinal cord with similar characteristics to the evoked depolarization wave. The spontaneous wave originated in multiple locations including two restricted regions located in the dorsomedial pons and rostral ventrolateral medulla as well as the media/caudal medulla and spinal cord. When the spinal cord was intact, the wave at E16 mainly originated in the lumbosacral region, although a wave associated with the oscillatory event was also generated in the cervical cord/caudal medulla. In preparations in which the spinal cord was transected, the contribution of the pons and medulla was more significant. These results show that the depolarization wave is triggered by the spontaneous activity of multiple neuronal populations which distribute widely from the pons to the lumbosacral cord. The network possibly behaves as a self-distributing system that maintains the incidence and complicated patterns of the correlated activity in the developing CNS.